The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Powertrain systems including hybrid powertrains, electric vehicles, and extended range electric vehicles are configured to operate in a plurality of operating modes. Such powertrain systems use torque generators, clutches and transmissions to transfer torque to a driveline. Executing a shift from an initial operating mode to a target operating mode may include executing a direct shift process that includes deactivating an off-going clutch and activating an oncoming clutch. Known powertrain systems maintain propulsion torque during a shift by slipping either an oncoming clutch or an off-going clutch while synchronizing speeds of clutch elements of the oncoming clutch before fully applying the oncoming clutch, with an applied clutch that is common for the first and second states being continuously applied during the shift execution. Synchronizing the speeds of the clutch elements includes controlling operation of one or more of the torque generators to achieve a synchronization speed.
Known issues associated with executing a direct shift process include driveline power loss and energy loss during clutch application. The power loss during clutch slippage may be discernible by a vehicle operator.